Column chromatography of human small-intestinal maltase, isomaltase and invertase activities

1. The maltase, isomaltase and invertase (sucrase) activities of solubilized mucosal preparations from human jejunum and ileum were studied with column chromatography on anion-exchange (diethylaminoethyl- and triethylaminoethyl-)cellulose and Sephadex G-200 gel. 2. On ion-exchange cellulose columns both kinds of enzyme preparations yielded two major disaccharidase peaks. The first peak contained maltase Ia (=isomaltase) and maltase Ib (=invertase). The second peak contained maltase II and maltase III. 3. On Sephadex G-200 gel columns jejunal preparations yielded the corresponding peaks as on ion-exchange columns, but the peaks appeared in the reverse order in the effluent. The ileal preparation studied yielded a single peak on gel columns, containing all the activities studied and eluted with the ;void volume'. 4. Precipitation with ethanol did not affect the behaviour of the enzymes during ion-exchange chromatography. When gel filtration was performed after ethanol precipitation of the enzymes, however, two peaks were obtained also with the ileal preparation, and subfractionation of the invertase was obtained with both kinds of preparations. 5. The second peak from ion-exchange chromatograms, containing maltase II and maltase III, on concentration was found to have very weak isomaltase activity, probably exerted by these enzymes as such. This activity accounts for only about 1% of the total isomaltase activity of the mucosa. 6. The results support the concept of the specificity of the human small-intestinal disaccharidases previously described after heat-inactivation experiments. The subfractionation of the invertase that under certain conditions is seen on Sephadex G-200 columns appears most likely to be an artifact. Consequently the nomenclature for the human maltose-, isomaltose- and sucrose-splitting enzymes proposed by another research group after gel-filtration chromatography studies should be abandoned. It seems more logical to keep the nomenclature based on heat inactivation [maltase Ia (=isomaltase), maltase Ib (=invertase or sucrase), maltase II and maltase III] until increased knowledge about the specificity and structure of these enzymes makes possible a more rational nomenclature.

Carbohydrase activities in the bovine digestive tract

1. The carbohydrase activities of homogenates of mucosa from the abomasum, small intestine, caecum and colon, and of the pancreas of cattle were studied. 2. The disaccharidase activities were located mainly in the small intestine and showed a non-uniform pattern of distribution along the small intestine; trehalase activity was highest in the proximal part, lactase and cellobiase activities were highest in the proximal and middle parts and maltase activity was highest in the distal part. 3. The intestinal lactase and cellobiase activities were highest in the young calf and decreased with age, whereas the intestinal maltase and trehalase activities, which were very low compared with the lactase activity, did not change with age. 4. No intestinal sucrase or palatinase activity was detected in the calf or in the adult cow. 5. Homogenates of intestinal mucosa also exhibited amylase and dextranase activity. 6. Homogenates of the pancreas possessed a strong amylase activity and a weak maltase activity. The maltase activity did not change with age, whereas the amylase activity increased with age. 7. No marked differences were observed between the carbohydrase activities of calves fed solely on milk and those of calves given a concentrate-hay diet from 6 weeks of age.

Pharmacological responses of the isolated innervated intestine and rectal caecum of the chick

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Postnatal changes of activity and electrophoretic pattern of jejunal and ileal nonspecific esterase and alkaline phosphatase of the rat. Effect of adrenalectomy

During postnatal development of the rat, the activity of nonspecific esterase (substrate, β-naphthyl acetate) in the jejunum and ileum increased. Electrophoresis showed that distribution of this enzyme was different in these two parts of the intestine in the suckling rat, whereas the zymogram was the same for both parts in the adult rat. In intact animals, the degree of inhibition of nonspecific esterase activity by 10−4 M eserin, 5 × 10−8 M di-ethyl p-nitrophenyl phosphate (E.600), and 0.4 M NaCl was different, but there were no differences with any one inhibitor between the jejunum and the ileum of suckling and weanling rats. Adrenalectomy at 7 days of age did not influence the activity of the enzyme, but at 14 days of age it inhibited the rise of activity in jejunum and ileum. Adrenalectomy influenced the sensitivity of nonspecific esterase activity to inhibition by eserin and E.600. When cortisone was administered to adrenalectomized rats, certain characteristics of the enzyme (specific activity, sensitivity to various inhibitors, zymogram) were, in most case, comparable with those of preparations from normal controls.During postnatal development, the activity of alkaline phosphatase (substrate, β-naphthyl phosphate) in the jejunum showed practically no change, but in the ileum it decreased. Change in the zymogram was of the same type in both jejunum and ileum. Adrenalectomy at 7 days of age was followed by a fall in activity in the ileum that was apparent at 14 days of age, but the zymogram was not affected. Adrenalectomy on day 14 did not produce an apparent change by day 21, but there was retention of the earlier electrophoretic pattern. When cortisone was administered to adrenalectomized rats, certain characteristics of the enzyme (specific activity, zymogram) were comparable with those of preparations from normal controls.The results are discussed from the point of view of difference between the jejunum and ileum of suckling animals, and the influence of the adrenal glands.

Proteolytic and peptidase activities of the jejunum and ileum of the rat during postnatal development

1. Proteolytic (substrate nitrocasein), tripeptidase (substrate glycylglycylgly-cine) and aminopeptidase (substrate leucyl-beta-naphthylamide) activities were studied in homogenates of jejunal and ileal mucosa of 7-, 10-, 14-, 21-, 35- and 60-day-old rats. 2. Proteolytic activity was practically the same in jejunum of 7-, 10-, 14- and 21-day-old rats, but after day 21 a significant increase was observed. The activity of the ileum changed very little during postnatal development and was always higher than that of the jejunum. 3. Tripeptidase activity was low in the jejunum of 7- and 14-day-old rats, an increase was observed between day 14 and 21, but later no substantial changes were found. There were no changes in the ileum. The activity in the jejunum of 7- and 14-day-old rats was lower than in the ileum, but later the jejunum was more active than the ileum. 4. Aminopeptidase activity had a similar developmental pattern to tripeptidase activity. A low activity was found in the jejunum of 7- and 14-day-old rats, the maximum was in 21-day-old rats and then a decrease was observed, though values for 60-day-old rats were still higher than for 7- and 10-day-old rats. The activity in the ileum was practically the same in all age groups studied except in 14- and 21-day-old rats, where a transient peak was observed.